利用磷灰石裂变径迹研究鄂尔多斯盆地西缘热历史

THERMAL HISTORY STUDY IN THE WEST OF THE ORDOS BASIN USING APATITE FISSION TRACK ANALYSIS

磷灰石裂变径迹在地质时期对60～150℃范围内温度变化的热敏感性 ,不仅使其成为研究盆地构造热演化史和区域构造运动的重要手段 ,而且对指导油气勘探有很大的实践意义。本文根据AFTA① 的有关原理 ,退火特性 ,对鄂尔多斯盆地西缘奥陶、二叠、三叠、侏罗、白垩、第三纪等不同时代地层样品开展了较为系统的AFT测试 ,获得了一批可靠的AFTA数据 ,论述了鄂尔多斯盆地西缘的主要构造热事件的次数 ,及该区中生代以来的构造热演化史。研究表明 :自中生代以来 ,该盆地西缘至少经历了四次构造热事件(峰值年龄分别为170Ma±、130Ma±、和75Ma±和17Ma±)。

For apatite has thermal sensitivity between 60 ℃to 150 ℃in geological time,the method of apatite fission track analysis not only is a main way to study the thermal history of sedimentary basins and tectonic movement,but also has important practical meaning in oil/gas exploration guide.Based on collected specimen of the Ordos basin,this paper applies the method of apatite fission track analysis to determine the age, and gets believable AFTA age data.In combining with former AFTA,TL and paleogeothermal gradient′s data,the thermal history of the Ordos basin,especially of the western area of the basin is discussed.The results show that the basin has experienced four thermal events at least since the early Mesozoic whose peak age is 170 Ma,130 Ma,75 Ma and 17 Ma respectively.